Chemistry

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Start date: 2009Subject: search.filters.subject.Aspergillus flavus

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    In vivo and in silico Antifungal Activity of Cinnamon Leaf Oil and Lemongrass Oil containing Chitosan Microcapsules against Aspergillus flavus
    (2024-04) Kumarathunga, P.G.J.D.; Chathurangi, S.; Rajapaksha, R.P.S.P.; Sooriyawansha, A.M.S.C.; Jayawardena, P.A.S.N.P.; Dananjaya, P.D.H.; Alwis, M.D.N.; Kadigamuwa, C.C.; Dahanayake, J.N.; Wickramarachchi, Suranga
    This study aimed to examine the potentiality of microencapsulated cinnamon leaf oil (CNO-CS-MCs) and lemongrass oil (LGO-CS-MCs) as natural fungicides against Aspergillus flavus. Oil encapsulated microcapsules were synthesized using ionotropic gelation method. Cinnamon leaf oil (CNO) and lemongrass oil (LGO) were characterized using GC-MS. A. flavus was isolated and identified using DNA sequencing. The minimum inhibitory and minimum lethal doses of oil-loaded microcapsules against A. flavus were evaluated under in vivo conditions and the results were further confirmed by in silico analysis. The major constituents of CNO and LGO were eugenol and citral, respectively. The minimum inhibitory doses of CNO-CS-MCs and LGO-CS-MCs were 5 mg and 7.5 mg, respectively. The minimum lethal dose of CNO-CS-MCs was 12.5 mg. As CNO showed considerably high antifungal activity than LGO, Computational investigations were carried out on the action of CNO against A. flavus. The highest protein-ligand interaction was observed for squalene epoxidase (SQ)-benzyl benzoate (BEN) complex with the binding energy of -7.70 kcal/mol. Molecular dynamics simulations were performed on SQ-BEN complex for 10 ns using CHARMM36 force field. The Rg, RMSD and RMSF results indicated the stabilization of the SQ-BEN complex throughout the simulation time.
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    Aflatoxigenic Aspergillus flavus and aflatoxin formation in selected spices during storage
    (2009) Rajasinghe, M.; Abeywickrama, K.P.; Jayasekera, R.
    Proliferation of aflatoxigenic fungi and accumulation of aflatoxins take place during storage of spices at various environmental conditions. The objective of this research was to identify the aflatoxigenic fungal species and their aflatoxin forming potential in selected spices during storage in the laboratory and refrigerator. Dilution series of spice samples namely chilli (Capsicum annum) powder, curry powder, turmeric (Curcurma longa) powder and pepper (Piper nigrum) powder (purchased from two producers) were prepared separately and the frequency of occurrence of aflatoxigenic and other fungi were assessed after plating each on Potato Dextrose Agar and incubating at ambient temperature. Aflatoxin formation of A. flavus was confirmed by growing a pure culture on a SMKY medium and identifying toxins on thin layer chromatographic plates. The presence of aflatoxins in spice samples stored at 30 ± 20C and 40C was also confirmed. Long storage of spices leads to aflatoxin production irrespective of storage temperature hence, it is advisable to consume spices such as chilli powerder, tumeric etc. within a relatively short period to avoid build up of aflatoxins.